Semiconductor devices and integrated circuit devices in particularly usually have a semiconductor chip mounted on a lead frame. After attaching the semiconductor chip to the lead frame the device is encapsulated. A large portion of the lead frame is then removed leaving individual leadframe leads attached to the contact areas of the chip.
Various techniques have been used in attaching leads to a semiconductor device. In one process, a small bond pad is utilized to attach the semiconductor chip to a larger lead frame which subsequently get trimmed leving only the leads. Tape Automated Bonding (TAB) uses a carrier ring to permit mass bonding of devices, and then each the device is excised from the carrier ring and the leads trimmed and formed. In the Flip chip process, the semiconductor device or chip is bonded to another substrate using bump contacts grown or plated on the device and then reflowed to attach the device to the other substrate.
Lead frames add to the expense of packaging in that most of the lead frame is removed and the devices require encapsulating to keep the leads in place. In the TAB process there is the expense of growing bump contacts on the surface of the device and the cost of the tape to bond to the bumps. Most of the tape is cut away and is not used.